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TPS568215: Feedforward Capacitor Questions

Daniel Carlson
Prodigy 370 points
Part Number: TPS568215

Hello,

I have a customer who is using the TPS568215 for multiple output rails on their system, and they're wondering if there is any internal feedforward capacitance in the IC. There is an app note ( http://www.ti.com/lit/an/slva466a/slva466a.pdf?ts=1588208579544 ) that talks about an integrated FF cap in the TPS621- and TPS821- families, so I wanted to get confirmation as to the existence of an internal FF cap in the TPS568215. 

Secondly, there is a table (Table 5) in the TPS568215 datasheet that says a FF cap is not needed for output voltages below 3.3V. The output voltages in my customer's application will range from 0.9 - 2.5V, so I was wondering if there would be any significant benefit to add FF capacitance on these rails, or if the benefits would be negligible. 

Thanks for your help.

-Daniel

  • 0
    TI__Expert 7500 points

    Hi Daniel,

    TPS568215 doesn't have internal feedforward cap.

    The feedforward cap will induce one zero and one pole as below. So if the Vout is small, the zero and pole are very close to each other which will not promote the phase so much as higher Vout. So the benefits is small.

    Thanks,

    Lishuang